Looks good! I think your plan is sound and these old Miyata are fabulous riding bikes. I have had several including a 1000, 610, 710, 912, 110, and 2 310's. I think your is an 86. my 84 310 was one of my favorites, rode as well as the 1000, better than the 710, and I shouldn't have sold it to a friend. The switch to 700x28 will give you some more room for fenders.
If you are serious about rando the handbuilt wheels will serve you well.
Keep us posted.

Tom Palmer
Twin Lake, MI